TIM15 does not outpu pulses in OPM mode

I tried STM32F10x_StdPeriph_Lib_V3.5.0\Project\STM32F10x_StdPeriph_Examples\TIM\OnePulse examples after adding systick timer to generate 50Hz square wave looped back to timer input. This was easiest way to test it. It worked fine. Now I changed timer to TIM15 and made corresponding changes to turn on its clock and configuring appropriate GPIO pins. It does no work. I have spend hours on it back and forth between TIM4 and TIM15. Former works but later does not.

I also have another question: why does BothEdge does no work in input capture mode, what do I need to do to make it work.